1)Experienced brewers making great beer. A good selection/rotation of great beers.
2)Good location - for me, I prefer suburb locations as opposed to city. Easier to park, you dont get lost, and closer to home for many families.
3)Great food - I'd expect a real chef(s) on staff and some unique menu selections - Sushi & Beer anyone??
4)Reasonable prices - Pints under $3.00 and free tastes (within reason). Pitcher discounts. Don't overprice the food either. I'd bet many beer snobs are also amatuer gourmets who know the value of meals.
5)Educated Staff - who can answer people's beer questions correctly and with confidence.
6) Dynamic management - keeps beer selection & menu fresh and progressive.
7) "Around the world club" - Do something to show appreciation for the better customers (name on plaque on wall, etc) when they reach certain milestones.
Great Wings!!!!!! At least in my corner of the world, wings can make or break a restaurant/bar.
9) Great Pizza!!!!!! Same reason as above.
10)Consideration to families - Provide some "out of the way" seating for those of us with squawking newborns. Outdoor/deck seating is a big +++.

Things I don't want

1) Watery crappy beers that all have a similar bad taste.
2) Crappy, bloating, typical bar foods that will not impress your wife/date into wanting to let you come back.
3) Brewers that put personal preferences ahead of appropriate treatment of their recipes( i.e. John Harvards in Monroeville, PA seems to use oak chips or something in many of their beers which is a turn off for certain styles.)
4) High Prices!!- if I can't afford the beer/food, I'll stay home and drink homebrew and grill steaks.
5) Un-trained staff who insults our beer snob intelligence by incorrectly describing styles.
6) Too much exposure to the process - No one wants to sit and shmooze their date next to a fermentor that reaks of two day old stale ale.
7) Lack of hot sauce. I can't even eat a bar pretzel unless it's slathered with tabasco.
Too much stupid nostalgia - it's a brewpub, not a museum.
9)Too bright/pristine atmosphere. I think dark wood goes good with beer, and leave the floors a little dirty.
10)As with any business, poor service is very difficult to overcome. Many people are stubborn enough to boycott a place due to one bad experience.

Andytv just about covers it but I have a few more suggestions.
Good:
Beer Selection - This one is huge. Make a few beers that will be your old standbys design them with many palates in mind then rotate different seasonals as close to style as possible. The brewpub we have here does this and I actually look forward to see whats new and tasty. Anticipation is a wonderful sales tool.
Also make a light beer with a little more flavor than an American Lager ( Blonde, Pils or some other light lager ). There's nothing better to help convert those light lager folks than something that tastes close to what they are used to ( if they like it they may try something else ). Too many times I have had friends turn down my favorite pub because they didn't like the style of beer.

I whole heartily agree with everything said so far, my main gripes of the brew pubs here in Brisbane is that they look more like trendy bars than pubs, or, they go the "Irish look", the beers too cold - cant taste the hops in a pale ale and the staff know nothing about the product.If you own a brew pub then interested enthusiasts like myself are going to visit.
And in my opinion, a great pub is demonstrated by the diversity of its clientel. And NEVER change the decor!!!!!!! i will quite happily retire to a dark corner with a favourite pint and observe/ chat , whatever, familiarity is the key, and may i please add that i REALLY miss my pub back in London.

I think that I totally agree with all that has been said, so I will just mention 1 or 2 things. 1. Price--I dont want to pay more than $3 for a pint. 2. Great beer deserves great food. 3. Gotta have the dart boards and pool tables, I can't stand to just sit around and drink, I have to have something to do. Conversation can only go so far, then all you have to talk about is the weather.
Now that I'm a daddy, there has to be many different areas for all of your different kinds of patrons. If there is smoke, my baby won't be there, which probably means my wife and I wont be there. Music is nice once in a while, but have somewhere for me to sit if I dont like the band.
Enough said, its time for bed. Salut.
Ed